/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.lucene.util;

/**
 * An object with this interface is a wrapper around another object (e.g., a filter with a
 * delegate). The method {@link #unwrap()} can be called to get the wrapped object
 *
 * @lucene.internal
 */
public interface Unwrappable<T> {

  /** Unwraps this instance */
  T unwrap();

  /** Unwraps all {@code Unwrappable}s around the given object. */
  @SuppressWarnings("unchecked")
  static <T> T unwrapAll(T o) {
    while (o instanceof Unwrappable) {
      o = ((Unwrappable<T>) o).unwrap();
    }
    return o;
  }
}
